Currently, during manufacture of a color filter (CF) substrate, each of a black matrix (BM), red, green and blue (R, G, B) sub-pixels and pillar-shaped spacers (PS) is formed by way of post-curing, e.g., heat curing, after development. It is required for high-resolution display panels to have a smaller line-width of the black matrix, which is fabricated by using a photoresist after being subjected to spin-coating, exposure and development. The black matrix structure obtained by fabrication is shown in FIG. 1, and a black matrix 1 appears to be an inverted trapezoidal structure as a whole, which is hard in top and soft in low. When a post-curing process such as heat curing is executed, photoresist (i.e., PR) is heated to soften and flows downward, which will cause line-width of the BM 1 become broad, as shown in FIG. 2, and requirements for high-resolution display panels cannot be met. Moreover, the requisite time period for heat curing is longer, and the production efficiency is low.
For the sake of solving the above issue that the BM line-width broadens, it is possible to use an existing back exposure technique to strengthen the curing of the PR in the lower part of a BM, so as to maintain the inverted trapezoidal structure formed after development. However, the structure may still deform after it is baked with heat, causing the BM line-width broaden, and thus the issue that the BM line-width broadens cannot be solved nicely.